Please referring to FIG. 1, a conventional stringed instrument such as a guitar has a string winding means located thereon to adjust the looseness and tightness of strings. Also referring to FIG. 2, the conventional string winding means of a guitar includes a hollow seat 1 and a duct extended longitudinally from the bottom of the seat 1 to couple with a winding shaft 2. The winding shaft 2 has an upper end engaged with a worm gear 3 located in the seat 1 and a string hole at a lower side threaded through by a string for fastening. The seat 1 has a transverse axle duct 4 run through by a worm 5 which is engaged with the worm gear 3 to drive the worm gear 3 to turn. The worm 5 has a coupling portion 5a at one end with two opposite flat surfaces, a turning peg 6 with a hole formed in the center that also has two flat surfaces opposing each other to couple with the coupling portion 5a, a screw 5b fastened from outside to a screw hole formed in the coupling portion 5a to fixed the turning peg 6 on the worm 5. The winding shaft 2 has a screw hole 2a in the center of an upper end thereof fastened by another screw 7 to form secure positioning of the winding shaft 2. The seat 1 further has an opening 8 at the top covered by a sealing lid 9.
By turning the turning peg 6 to drive the worm 5 to turn in a positive direction or a negative direction the worm gear 3 can be turned in the positive direction or the negative direction, and the winding shaft 2 also can be turned in the positive direction or the negative direction, thereby the looseness or tightness of the strings of the guitar can be adjusted as desired.
However, the conventional string adjustment means of guitars consists of a great number of structural elements, and the winding shaft 2 and the worm gear 3 have to be fabricated separately. Moreover, the turning shaft 2 has to be coupled on the seat 1 by fastening the screw 7 at two ends of the duct, and to avoid the screw 7 from exposing that could spoil the appeal the opening 8 has to be covered by the sealing lid 9, all this requires extra elements and results in a higher cost. Moreover, the complicated structure makes assembly through automation equipment impossible, and manual assembly has to be adopted. This further increases the cost. Hence the selling price also is higher that seriously affects competitiveness on the market.